Stabilized load hoist apparatus

ABSTRACT

Hoist apparatus for moving a load between relatively vertically movable locations, wherein the load is moved by a pair of load hoist cables, and a tension hoist cable is connected between the relatively vertically movable locations, the load hoist and the tension hoist being coupled together to cause movement of the load corresponding to the movement between the locations, the load hoist also being operable to move the load between such locations, the load being connected to the pair of load hoist cables and being guided on the tension hoist cable.

[ Mar. 14, 1972 United States Patent Barron et al.

em mu n vh mm JP. 0 6 9 l 7 [54] STABILIZED LOAD HOIST APPARATUS2,609,181 9/1952 [72] Inventors: Charles D. Barron, Huntington Beach;2/1971 Earl A. Peterson, Long Beach; Gary K. Stark, Buena Park; Carl A.Wilms, La Habra, all of Calif.

Primary Examiner-Gerald M. Forlenza Assistant Examiner-Frank E. WernerAtt0rneyDonald W. Banner, William S. McCurry and John W. Butcher [73]Assignee: Byron Jackson lnc., Long Beach, Calif.

[22] Filed: May 7, 1970 [21] Appi. No.: 35,370 ABSTRACT Hoist apparatusfor moving a load between relatively vertically movable locations,wherein the load is moved by a pair of load hoist cables, and a tensionhoist cable is connected between the relatively vertically movablelocations, the load hoist and the tension hoist being coupled togetherto cause movement of the load corresponding to the movement between thelocations, the load hoist also being operable to move the load betweensuch locations, the load being connected to the pair of load hoistcables and being guided on the tension hoist cable.

2,854,154 9/1958 l-lepinstall................................2l4/l41,999,936 4/1935 Lange.....,..............................254ll7211Claims,7DrawingFigures PATENTEUMAR 14 1912 3.648 858 SHEET 5 [IF 5CAEL ,4. l V/MS INVENTORS.

(QM L.

ATTOZA/y STABILIZED LOAD IIOIST APPARATUS BACKGROUND OF THE INVENTIONProblems are encountered in loading or unloading personnel or equipmenton or from a floating transport vessel which is subjected to wave actioncausing upward and downward movements of the vessel relative to anotherlarger vessel or barge or platform, such as, for example, at offshorewell drilling or producing sites. Damage to the transport vessel or tothe personnel or equipment may occur because of thedifficultyencountered when the transport vessel is rapidly rising orfalling.

THE PRIOR ART Heretofore, as disclosed in the pending application forUS. Pat., Ser. No. 19,582 filed Mar. 16, 1970, motion compensating hoistapparatus has been provided for moving the load between the twolocations such as between a well drilling platform or barge at sea and avessel used to transport men and equipment to and from the platform orbarge, wherein the load is caused to move vertically in synchronism withthe vessel, so that the load can be conveniently and also safely movedrelative to the vessel. Such apparatus facilitates the movement ofpersonnel or equipment onto or from the vessel notwithstanding the factthat the vessel may be caused to move vertically by the action of wavespassing beneath the vessel.

More particularly, a load hoist and a tensioning hoist are provided andare adapted to be coupled together so that the motion of the transportvessel is imposed on the load, but the load may also be moved relativeto the vessel by the load hoist. In such a hoist system the tensionhoist has a tension line connected to the vessel and a fluid pressureactuated slip clutch drives the tension hoist to apply a substantiallyconstant tension to the tension line and the load hoist is coupled tothe tension hoist, the rise and fall of the vessel causing a variablecontrol signal to be supplied to a fluid pressure controller to vary thepressure of actuator fluid supplied to the clutch. The load slidablyengages the tension line so as to be guided to and from the deck of thetransport vessel.

SUMMARY OF THE INVENTION As the load, supported by the load hoist cable,is moved synchronously with the transport vessel under the influence ofwaves acting on the transport vessel, it is possible that the load maybe caused to swing and possibly cause wrapping or snarling of the loadline and the tension line.

Accordingly, the present invention provides a motion compensating hoistsystem, wherein the load is substantially stabilized by at least threelines which are connected to the load in spaced relation, certain of thelines supporting the load and other of the lines guiding the load,whereby the load is substantially stabilized against swingingabouteither line.

To accomplish this, one of the load and tension hoists has two drums andtwo cables or lines which are guided in axially spaced sheaves on theboom which projects from the platform or barge, and the other hoist hasits cable or line guided in an intermediate sheave, whereby the threecables or lines can be connected to and slidably engaged with the loadto stabilize the load. More particularly, the load hoist preferably hastwo drums and cables or lines, so that as a safety precaution theload'is supported by two cables,-and the load slidably engages theintermediate tension line. However, it will be apparent thatequivalently a pair of tension hoist drums and cables or lines and asingle load hoist drum and cable or line could be employed to accomplishthe same results.

In either case, the load hoist and the tension hoist are adapted to becoupled so as to be driven together by the same power source, through aslip clutch which, on the one hand, allows downward movement of thevessel to pull cable or line from'the tension hoist and correspondinglycause load cable or line to be played off of the load hoist, and which,on the other hand, causes the load hoist to reel in cable or line at arate determined by the allowable reeling of tension cable or line ontothe tension hoist as the vessel moves upwardly, and in addition, a loadhoist drive is provided to separately move the load relative to thevessel when the load hoist and tension hoist are coupled or uncoupled.

This invention possesses many other advantages, and has other purposeswhich may be made more clearly apparent from a consideration of a formin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification. It will nowbe described in detail, for the purpose of illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed description is not to be taken in a limiting sense, since thescope of the invention is best defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective, fragmentaryview, sh,0wing a platform or barge above the water and equipped with theinvention for moving a load to or from a boat afloat in the water;

FIG. 2 is an end elevation of the power unit and the hoist and tensionwinches;

FIG. 3 is a fragmentary detail view, on an enlarged scale, with partsbroken away and showing the connection of the load hoist lines and thesliding connection of the tension line to the elevator;

FIG. 4a is a fragmentary view in side elevation, as taken on the line4-4 of FIG. 2, on an enlarged scale, and showing a portion of the hoistmeans with parts broken away to expose the drive for the tension winch;

FIG. 4b is a fragmentary view, as taken on the line 4-4 of FIG. 2,constituting a lateral continuation of FIG. 4a, and showing theselective drive connection of the tension winch to the load hoist;

FIG. 4c is a fragmentary view, as taken on the line 4-4 of FIG. 2,constituting a lateral continuation of FIG. 4b, and showing the motioncompensating drive for the load hoist; and

FIG. 5 is a diagrammatic illustration of the combined winches andcontrol means therefor.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGS. 1 and2, there is generally illustrated a barge or platform P adapted to besupported above the water on a number of suitably located legs L whichextend to the bottom of the water, and on which the platform or barge Pis mounted. In the case of certain barges, the platform is adapted to beelevated to a selected height above the water on the legs L, a distanceof feet more or less. On the barge or platform may be located the usualwell drilling and/or completion or workover apparatus (not shown), as iswell known in the art.

Periodically, the workers on the platform must be transported betweenthe platform and the shore, and in addition, it becomes necessary fromtime to time to move various gear between the shore and the platform.Thus, a boat or vessel V is in part illustrated, and such boats orvessels range considerably in size from comparatively large work boatsadapted to move heavy gear and supplies between the shore and theplatform, and small personnel carrying boats. In either case, problemsare experienced in transferring the gear or personnel between the vesseland the platform.

When the weather is fair and the water is calm the problem is lesspronounced, but, when the water becomes rough and swells tend to causethe boat or vessel V to rise and fall relative tothe platform theproblem is more pronounced. The greater the frequency of the swells theworse the problem, so that under many commonly encountered conditions,the transfer of equipment or personnel between the platform and the boator vessel V is very difficult, if not impossible to accomplish.

The present invention contemplates a motion compensating hoist system.whereby an elevator E or other load support is adapted to be raised orlowered between the outer extremity of a boom B and the vessel V, theelevator E being suspended by a pair of load hoist cables or lines 10a,10b. A tensioning line or cable 11 extends between the outer extremityof the boom B and a point of attachment 12 to the deck of the boat orvessel V. The lines or cables a, 10b and 11 respectively, are controlledby load hoist means LH and tensioning hoist means th, whereby during theinitial stages of the lifting of the elevator E from the deck of thevessel V and during the final stages of movement of the elevator E ontothe deck of the vessel V, the elevator is caused to move synchronouslywith the vertical movement of the vessel V, i.e., the elevator E movesin the same direction and at the same rate that the vessel V moves, asthe vessel V is subjected to wave action. Superimposed on thesynchronous movement of the elevator E with the vessel V is independentmovement of the elevator E in a controlled manner whereby the elevator Eis moved smoothly and gently to or from the deck of the vessel V by theload hoist means LH. The load hoist means LH is also operable, when theelevator E is moving through the portion of its travel safely above thedeck of the vessel V to independently cause vertical traverse of theelevator E.

More particularly, the boom B is mounted on suitable support structure13 which is affixed to a side of the platform P. The boom comprises inthe illustrative embodiment a pair of laterally spaced outwardlyconvergent V-shaped arms 14 and 15, which are preferably fabricated fromupper and lower rails 16 and 17 reinforced by suitable struts 18 forrigidity, the arms 14 and being suitably connected to the supportstructure 13. Also supported on the support structure 13 is a power unitplatform 20 on which is mounted a power source, such as an engine 21,adapted through a suitable reduction gear box 22 and a chain drive 23,by way of illustration, to drive the hoist means consisting of thetensioning hoist means TH and the load hoist means LH previouslyreferred to. At a suitable elevated and laterally displaced positionrelative to the support structure 13 is mounted a control cab C in whichan operator has good vision of the hoisting operations. Located betweenthe boom arms 14 and 15 and extending from the support structure 13horizontally to a location below the outer extremity of the boom B is awalkway W, having a laterally enlarged loading deck 26 at its outerextremity. The walkway W, the power unit platform 20, as well as thebarge or platform P are all provided with suitable guard railsthereabout, and a stairway 27 leads between the deck of the platform orbarge P and the power unit platform 20.

The load hoist lines or cables 10a, 10b extend from load hoist drums28a, 28b outwardly of the boom B and over sheaves 29a, 29b which arerotatably supported at the outer extremity of the boom. The load hoistlines 10a and 10b are connected to the top of load supporting meansshown as an elevator E, and more particularly, the elevator E hasequalizing means 30, best seen in FIG. 3, which allow the elevator tohang vertically, notwithstanding any tendency of one of the load lines100 or 10b tending to wind on or unwind from its drum 28a, 28b,respectively, at a greater rate than the other load line. Preferably,the lines 10a, 10b are constituted by a single length of line or cablethe ends of which are respectively wound on the load hoist drums 28a,28b, and the bight 31 of which engages the equalizing means including apair of spaced rollers 32, 32 carried by a support member 33 which spansthe elevator E and is welded or otherwise affixed to the elevator.

The tensioning line 11 leads from the tensioning hoist drum 34 along theboom B and over a sheave 35 which is suitably rotatably supported at theouter extremity of the boom. The tension line extends through a guide ortube 36 which is centrally disposed in the elevator. Thus, the elevatorE is supported at spaced locations by the lines 10a and 10b and guidedon the intermediate tension line 1 1, so that the load elevator iseffectively stabilized against swinging or spinning, and wrapping of thelines one about the other is precluded. In addition, the elevator orother load will be guided to and from the deck of the vessel V, eventhough the vessel may tend to move relative to the barge or platform P.

Referring to FIGS. 40, 4b and 4c, it will be seen that the supportstructure for the hoist means includes four laterally spaced uprights orposts 40, 41, 42 and 43. The uprights 40 and 41 have mounted thereon apair of laterally spaced bearing blocks 40a and 41a in which isrotatably joumaled a horizontally extended tensioning hoist shaft 44.The tensioning hoist means TH includes the drum 34 on which thetensioning line or cable 11 is wound, the hub 45 of the drum 34 beingkeyed as at 46 to the shaft 44 for rotation therewith. The shaft 44extends through the bearing block 40a to provide a driven shaft end 48adapted to be driven by the drive means 23 under control of slip clutchmeans SC.

More particularly, the drive means 23 includes a drive chain 49 adaptedto be driven by the output sprocket (not shown) of the reduction gearbox 22 of the power source 21. This chain 49 is engaged with a sprocket50, the hub 51 of which is rotatably mounted on the shaft end 48 bybearings 52. Affixed to the sprocket 50, is a disc 54 which is in turnaffixed by fasteners 55 to the outer periphery of the backup plate 56 ofthe slip clutch means SC.

This slip clutch means SC includes an outer annular body 57 to which anannular flange 58 is connected by fasteners 59 in opposed relation tothe plate 56. Internally thereof, the body 57 has a splined connection60 with the outer periphery of an axially shiftable clutch pressureplate 61. Between the clutch plates 56 and 61 is a clutch friction disc62 having friction facing 63 on opposite sides thereof and having, as at64, a splined connection with a hub 65 which is disposed upon the shaftend 48 and is keyed thereto by a key 66. Thus, rotation from thesprocket 50 will be transmitted to the tensioning hoist shaft 44 whenthe slip clutch means SC is engaged to transmit rotation from the clutchbody 57 and its plates 56 and 61 to the friction disc 62.

Engagement of the slip clutch means SC is accomplished by an annularexpansible actuator tube 67 having an air inlet 68. The actuator tube 67engages an annular body of insulating material 69 interposed between thetube 67 and the clutch pressure plate 61. Each of the clutch plates 56and 61 has a number of annular radially spaced and concentric coolantpassages 56a and 61a to which a coolant is supplied to dissipate theheat of friction caused by slippage of the clutch SC. These passages 56aand 61a are defined respectively between the clutch plates and wear disc56b carried by the plate 56 and wear disc 61B carried by the plate 61,the friction material on the friction disc 62 being engaged with thewear discs 56b, 6112.

Such cooled, slip clutches are well known, and generally are providedwith a coolant circulating system including a sta tionary coolantconnector 71 through which coolant flows to and from a rotary connector72 which is connected, as by fasteners 72a, to the clutch flange 58 andwhich has conduit means 73 for supplying coolant to the passages 56a and610, as well as conduit means for the return flow of coolant to theconnector 71 and thence to a heat exchanger. In addition, the rotaryconnector 72 provides a connection for air conduit means 74 which leadsto the air inlet 68 for the clutch actuator tube 67 from a stationaryair inlet fitting 75. As is well known, the torque transmitting capacityof such slip clutches varies with the pressure of air in the actuatortube 67.

Preferably, the slip clutch means SC is made in accordance with thedisclosure of US. Pat. application Ser. No. 19,601, filed Mar. 16, 1970,in the name of C. D. Barron, so that the clutch plates and discs aremore effectively cooled.

Referring to FIGS. 4b and 4c, it will be seen that motion compensatingdrive means are adapted to selectively drivingly connect the shaft 44 ofthe tensioning hoist means TH to a shaft 44a which is in turn drivinglyconnected to a shaft of the load hoist means LI-I. This shaft 80 ispreferably in two parts connected by a chain or other coupling 80amounted for rotation in bearings 40b, 41b, 42b and 43b which are mountedon the supports 40, 41, 42 and 43 so that the shaft 80 extends inparallel relation to the shaft 44 and the shaft 44a in laterally spacedrelation. It will be understood that the relationship between thetensioning hoist means and the load hoist means is only illustrative ofa preferred arrangement under given conditions, but that the shafts 44,44a and 80 may be otherwise arranged.

As seen in FIG. 4b, the shaft 44 has a chain or other coupling 81connected thereto by a key 82, the coupling also being connected to anadapter 83' which is in turn connected by fasteners 84 to an annularbody 85 of the motion compensating drive clutch means MC. The adapter 83and the clutch body 85 are revolvably mounted on bearings 86 on a sleeve87 which is splined to the end of the shaft 44a as at 88 for rotationtherewith. Typically, the clutch assembly MC. also includes a pluralityof clutch discs 89. Alternate discs 89 are splined to the adapter sleeve87, and the other discs 89 are splined to the annular clutch body 85,whereby rotation is transmitted to the shaft 44a from the shaft 44 whenthe discs 89 are engaged between the usual backup plate 90 and theshiftable pressure plate 91. In order to engage the clutch discs 89between the plates 90 and 91, actuator means responsive to fluidpressure are provided, including a thrust bearing 92 which is engagedwith the pressure plate 91 to shift the latter towards the backup plate90 in response to corresponding movement of an outer actuator sleeve 93which also is engageable with the thrust bearing 92. This actuatorsleeve is slidable on a fixed actuator sleeve 94 within which theadapter sleeve is rotatable on a bearing 95. These actuator sleeves 93and 94 are suitably formed and sealed to provide a pressure chamber 96to which fluid, such as air, may be admitted through a conduit 97 toeffect engagement of the clutch MC, or to allow its release in theabsence of pressure fluid.

As also seen in FIG. 4b, the shaft 440 has a brake 100 adapted to brakethe shaft 440 when the clutch MC is disengaged. This brake 100, in theillustrative embodiment, is like the clutch MC. More particularly, thebrake 100 includes an adapter 101 which is fastened, as at 102, to astationary plate or flange 103 which is suitably affixed to the support42. A pin 104 connects the adapter 101 to an annular brake body 105, andan adapter sleeve 106 which is splined to the shaft 440, as at 107, isrevolvable in bearings 108 within the adapter 101 and the brake body105. A pack of discs 109 are disposed between a backup plate 110 and apressure plate 111, and alternate discs 109 are splined to the body 105and the sleeve 106, whereby to hold the shaft 44a against rotation whenthe brake 100 is engaged. To engage the brake 100, a thrust bearing 112is interposed between the pressure plate 111 and an annular actuatormember 113 which is axially shiftable on an internal actuator member 114within which the shaft 44a revolves in a bearing 115. These actuatormembers 113 and 114 are formed and sealed to provide a chamber 116 intowhich pressure fluid is supplied through a conduit 117 to engage thebrake 100.

As will hereinafter be more fully described, the clutch MC and brake 100are preferably supplied with actuating fluid pressure simultaneously, sothat when the brake 100 is engaged, the clutch MC is released, and viceversa. When the clutch MC is engaged, rotary motion will be transmittedfrom the shaft 44a to the shaft 80, in the direction and at the ratedetermined by operation of the tension hoist TH and the slip clutchmeans SC.

As seen in FIG. 40, rotation o the shaft 44a is not only adapted to betransmitted to the shaft 80 of the load hoist, but, in addition, theload hoist shaft 80 may be further driven to superimpose a traversemovement of the elevator E on the compensating movement. In thisconnection, the shaft 44a extends through a bearing 43a carried by thesupport 43 and has a sprocket 120 carried by a hub 121 and revolvableabout the shaft 44a on bearings 122. A chain 123 is engaged with thesprocket 120 and with a similar sprocket 124 which is keyed, as at 125,on the shaft 80. Motor brake means 126 are provided to connect thesprocket 120 to the shaft 44a to drive shafts 44a and 80 in unison andto further, separately drive shaft 80.

A plate 127 is keyed on the shaft 44a by a key 128, and a gear 129having external teeth thereon is fixed on the hub 121. Motor means 130and brake means 131 are carried by the plate 127 and are selectivelyoperable to drive the gear 129, and hence the drive sprocket 120,simultaneously synchronously with and oppositely relative to the shaft44a, or to lock the gear 129, and hence the drive sprocket 120 and theplate 127 together for unitized rotation.

More particularly, the motor means 130 includes a housing 132 connectedby fasteners 133 to the plate 127 and an output shaft 134 which extendsthrough the plate 127. On the output shaft 134 is a pinion 135 which isdrivingly in mesh with the external gear teeth of the gear 129. Fluid issupplied to the motor 130 in selected, reversible directions throughconduits 136 and 137 to effect reverse operation of the motor, suchfluid being supplied through passages 136a and 137a which extendlongitudinally in the shaft 44a and are supplied from stationary sourceconduits 136b and 137b, respectively, which are connected to a rotaryfluid connector 138 suitably mounted in a housing 139, as by fasteners146. Such a rotary connector 138 is common and requires no furtherspecific discussion. The motor 130 also has a fluid outlet 141 which, aswill be more fully described hereinafter, supplies fluid to the inletconduit 142 of the brake means 131 to release the latter when the motor130 is operating, whereby the load hoist shaft 80 is revolvable whetheror not the shaft 44a is revolving. When the motor means 130 isoperating, the net rotary motion of the shaft 80, is a function of thedirection and extent of rotation of the shaft 44a modified by thedirection and extent of rotation of the gear 129 about the shaft 44a ineither direction. Therefore, the load hoist lines 10a and 10b and theelevator E may be raised or lowered by the motor 130, while the lines10a and 10b are also moving the elevator E in unison with movement ofthe boat or vessel V.

The brake means 131 comprises a housing 145 secured to the plate 127 soas to revolve with the shaft 440. Carried by and disposed in the housing145 is a rotatable stub shaft 146.

I This shaft 146 extends through the plate 127 and has a pinion gear 147keyed thereon and engaged with the gear 129. A brake rotor 148 is keyedon the shaft 146, and friction discs 149 are interposed between thebrake rotor 148 and an actuator member 150, alternate discs beingsplined to the rotor 148 and to the housing 145, so that when the discsare engaged, the rotor 148 will be held stationary, thereby holding thepinion 147 against rotation, to brake the gear 129, and hence the loadhoist shaft 80. The brake 131 is normally engaged by a number of coiledcompression springs 151 spaced circumferentially of the actuator member150 and acting on the same and on an internal flange 152 in the housing145 to bias the member 150 in a brake-engaging direction. To disengagethe brake means 131, fluid under pressure is supplied from the conduit142, previously referred to, to a sealed piston chamber 153 in which isa piston 154 connected to the actuator member 150, as by screws 155, tomove the actuator member 150 to a brake-release position. When the brakemeans 131 is engaged, the hoist shaft is effectively connected to theshaft 440 for rotation therewith, but when the brake means 131 isreleased, the motor means 130 is effective to not only connect the shaft44a to the shaft 80, but also to effect relative rotation thereof, aspreviously described.

OPERATION It will now be apparent that when the slip clutch means SC isengaged to apply tension to the line 11, the tension hoist drum 34 willbe caused to rotate to play out line when the vessel V descends, and thedrum 34 will be rotated in the other direction to take up line when thevessel rises, such rotation of the drum 34 in either direction being ata rate determined by the rate of vessel movement. When the motioncompensating clutch means MC is engaged, corresponding rotation will betransmitted through the shaft 44a to the motor-brake means 126 andthence through the sprockets and 124 to the load hoist shaft 80 and itsload hoist drums 28a and 28b, whereby the load or elevator E will movesynchronously with the vessel V. When the motor is also operated,further movement of the elevator will be effected to move the elevatorduring that portion of its travel close to the vessel. The other portionof movement of the elevator is accomplished with the motion compensatingclutch MC released and the brake 100 engaged to hold shaft 440stationary, as the motor 130 is operated to raise or lower the load orelevator E.

The operation of the load compensating hoist system will be furtherunderstood with reference to FIG. 5, wherein the apparatus isschematically illustrated together with operating and control meanstherefor. For convenience of illustration, the tension line is not shownas slidably engaged with the elevator E, but in practice would be soengaged, as previously described.

In this view, it will be noted that air under pressure is supplied tothe inlet connector 75 os the slip clutch means SC through a controlleror pressure regulator R1, so that the slip clutch means may be adjustedto transmit sufficient torque to the drum shaft 44 as to maintain apredetermined tension on the tension line 11 of the tension hoist meansTH which is connected to the vessel V. The controller R1 needs nospecific illustration, but is preferably of the type that will cause anoutlet pressure which is a function of a SET POINT signal and a signalderived from tension on the tension line 11. The line tension of thetension hoist TH is selected so as to be proportionate to load,represented by the elevator E, namely, the weight of the elevator Etogether with the weight of the load to be carried in the elevator, andinertia forces to be overcome in accelerating and decelerating the loadwhen the system is compensating for movement of the vessel V.

In order to cause motion compensating motion of the load lines 100 and10b, whether or not they are connected to a load or to the elevator, themotion compensating clutch means MC is engaged and the brake means 100is released. This is accomplished by suitable valve means, hereinillustrated as including a control valve CV1 which is interposed betweena suitable source of air under pressure and the pressure conduits 97 and117, the valve CV1 being operable in one position to connect the airsupply to both the clutch means MC to engage the same and the brakemeans 100 to release the same, and conversely, in the other position, toexhaust the clutch and brake to allow release and engagement thereof,respectively. Thus, with the clutch means MC engaged, the load hoistshaft 80 will be driven synchronously with the shaft 44 through chain123, and rotation of the load hoist shaft 80, which is locked to theshaft 44a by the motor-brake means 126, will be in the same directionand at the same rate as rotation of the tension hoist shaft 44, as thelatter is caused, alternately, to turn in one direction by the pull onthe line 11 by the vessel V, as the vessel moves downward, and in theother direction, as the vessel rises on a wave, the tension on line 11remaining substantially constant at the value established by the slipclutch means SC.

With the load hoist lines 10a and 10b thus moving with the vessel V, thelines 100 and 10b may be raised or lowered, whether or not connected tothe elevator E, by the operation of the reversible hydraulic motor 130,when the brake means 131 is released, whereby the load hoist drums 28aand 28b are subjected to a motion which is superimposed on the motion ofshafts 44 and 80 caused by the rise and fall of the vessel V.

To accomplish this, suitable valve means are provided, hereinillustrated as a control valve CV2, adapted to control the flow ofhydraulic motor fluid to the motor means 130 and to the brake means 131,and from the motor means to a reservoir. The valve means CV2 has aposition for directing fluid from a suitable pressure source throughconduits l36b and 136 and to an exhaust to cause motor rotation in ondirection, and another position for directing fluid through the conduits137b and 137 to cause motor rotation in the other direction. In eitherevent, pressure fluid is also supplied to the brake inlet conduit 142from a shuttle valve SV interposed between the conduits 136 and 137.

For moving the load hoist lines 10a and 10b independently of the tensionline 11, the control valve CV1 is operated to relieve operating airpressure from the clutch means MC and the brake means 100, so that thedrums 28a and 28b may be driven independently of the tension hoistmeans, to raise or lower the load lines 10a and 1017 when the load issafely above the vessel V, whether the lines 10a and 10b are loaded orunloaded.

With the foregoing in mind, it will now be understood that the tensionon the tension line 11 caused by the application of preset air pressureto the slip clutch means SC is preferably maintained at a constant valuewhether or not the load hoist lines 10a and 10b are supporting a load.Accordingly, load sensing means LS are provided to cause the applicationof a variable air pressure to the slip clutch means SC toadjust thetorque capacity of the slip clutch means SC so that the pressure supplyto the slip clutch means is decreased, if the tension on line 11 tendsto increase, or the pressure supply to the slip clutch means isincreased, if the tension on the line tends to decrease.

Such load sensing means may be any typical devices adapted to sense loadon a line to produce a related signal, such as a load cell of thehydraulic type, as indicated at 200 in FIG. 5. This load cell 200 has apiston 20] which projects from the cylinder 202 and is engaged by aportion 203 of a lever 204 which supports a tension line sheave 205 onthe axle 206, the lever being pivotally mounted on a pin 207 carried bythe support structure, as is obvious. Leading from the load cellcylinder 202 is a conduit 208 which is connected to a pressure regulatoror transmitter R2 of any suitable type which, as is well known, isoperative to regulate the drop in air pressure supplied from a sourceand establish an outlet air signal pressure pressure in a conduit 209which is a function of the applied hydraulic pressure from the loadsensor means LS. The air pressure from the regulator R2 is conducted bythe conduit 209 to the controller R1 to modify the net output pressurefrom the controller R1 to the slip clutch means SC.

Assuming that the vessel V, with a load thereon, such as certainequipment or personnel to be elevated to the platform P is situated at alocation below the boom B, the tension line 11 is lowered, either firstor with the load lines 10a and 10b, and the tension line 11 is connectedto the vessel V, with the line extending through the guide 36 of theelevator E. Air is supplied at a preset value to the slip clutch meansSC to apply a tension to the line 11 proportionate to the weight of theelevator E and any load which it is to lift. At this time, the rise andfall of the vessel V will cause the tension drum 34 to oscillate. Themotion compensating clutch means MC is engaged, and the drum shaft brakemeans correspondingly released, so that the load hoist drums 28a and 28bwill oscillate in unison with the tension hoist drum 34, causingsynchronous movement of the load lines with the tension line,corresponding to movement of the vessel. While such synchronous motionoccurs, the load hoist drum motor may be supplied with fluid, and thebrake means 131 is released, to enable controlled downward movement ofthe elevator E, or other load support, to the deck of the vessel forloading.

Thereafter, the motor 130 is reversed, causing upward movement of theload relative to the vessel, while the load continues to rise and fallsynchronously with the rise and fall of the vessel. As the load islifted from the deck of the vessel, the load will require substantiallythe full output of the slip clutch means SC which has been preset forthe known load value. Thus, there is a tendency to reduce the tension onthe tension line 11, which tendency is sensed by the load sensor meansLS. The reduced hydraulic signal from the load cell 200 causes anincrease in the air pressure supplied from regulator R2 to controller R1and a resultant increase in the air pressure supplied from the regulatorR1 to the slip clutch means until the torque capacity of the slip clutchSC is sufflcient to not only maintain the initial tension on the line11, but also to elevate the load, while the motion compensationcontinues. When the load is at a safe distance above the vessel, andmotion compensation is no longer necessary, the brake means 100 for theload hoist means are engaged and the motion compensating clutch means MCare released. At this time, since the slip clutch means SC no longer issubjected to the load, the entire torque for the slip clutch is appliedto the tension drum 34 tending to increase the tension, resulting in anincreased hydraulic signal to the regulator R2 and a reduction in thenet air pressure supplied to the slip clutch means to the originalpreset value, whereby the tension on line 11 will be held substantiallyat the constant predetermined value.

The lowering of a load onto the vessel will simply involve reversal ofthe operations described above in elevating a load.

During all of the travel of the elevator E between a location adjacentto the loading platform 26 of the boom B and a location on the deck ofthe vessel V, the sliding connection between the elevator E and thetension line 11 provided by the tube 36 and the spaced connection of theload lines a and 10b to the elevator E will prevent the elevator or theother load from spinning or wrapping a load line and the tension line.In addition, the load is guided to a precise location on the deck of thevessel, notwithstanding movement of the vessel beneath the end of theboom.

For the sake of safety, it will be understood that fail safe means (notshown) may be provided. In this connection, it is customary that hoistsor winches have normally engaged or spring-set band brakes associatedwith the drum, and more particularly with the flange 280 (FIG, 4c) ofthe hoist drum 28b, for example, and with the corresponding flange 34a(FIG. 4a) of tensioning hoist drum 34. Such brakes may be also employedin the present apparatus and released responsive to the fluid pressurein the operating system, so that the band brakes would automatically setin the event of loss of pressure in the system or any portion thereof.In addition, the brake means 100 and 131 may be employed as a fail safemeans for holding the load hoist against movement upon loss of operatingfluid pressure. Any such fail safe brake for the tension hoist TH shouldallow the line 11 to be played off of the drum 34 under tension appliedby fall of the vessel, so as to avoid any tendency to overload thetension line.

I claim:

1. ln motion compensating hoist mechanism including a support structureadapted to be mounted at a location over a vessel floating in the waterfor raising or lowering a load from or to said vessel, hoist means onsaid support structure including a load hoist and a tension hoist, drivemeans for releasably coupling said hoists for unitized operation, asource of power, slip clutch means for connecting said hoist means tosaid source of power for driving said hoist means, said tension hoisthaving cable means connectable to said vessel and slidably engaging saidload, and said load hoist having cable means connectable to said load,fluid pressure operated means for varying the torque transmittingcapacity of said slip clutch means, pressure controller means forvarying the actuating fluid pressure to said fluid pressure operatedmeans, and load responsive means for operating said controller means tovary the pressure of actuating fluid to increase the torque transmittingcapacity of said slip clutch means when the tension on said tensionhoist cable means decreases and to decrease the torque transmittingcapacity of said slip clutch means when the tension on said tensionhoist cable means increases, the improvement wherein the cable means ofone of said hoists includes a pair of cables, the cable means of theother of said hoist comprises a single cable disposed between said pairof cables.

2. In motion compensating hoist mechanism as defined in claim 1, saidcable means of said load hoist comprising said pair of cables.

3. In motion compensating hoist mechanism as defined in claim 2, saidpair of cables being connectable to said load, and including equalizermeans associated with said pair of cables and said load for allowingsaid load to hang vertically between said pair of cables when said loadhoist raises and lowers said pair of cables.

4. In motion compensating hoist mechanism as defined in claim 1, saidcable means of said load hoist comprising said pair of cables, a pair ofdrums disposed in axially spaced relation, said. pair of cablesrespectively being wound on said spaced drums.

5. In motion compensating hoist mechanism as defined in claim 1, saidload including a load support having guide means thereon, said cablemeans of said tension hoist slidably extending through said guide means.

6. In motion compensating hoist mechanism as defined in claim 5, saidload support comprising an elevator cage.

7. ln motion compensating hoist mechanism as defined in claim I, saidcable means of said load hoist comprising said pair of cables, and saidload including a load support slidably engaging said cable of saidtension hoist.

8. in motion compensating hoist mechanism as defined in claim 7, saidload support comprising an elevator cage having a central cable guide,said tension hoist cable extending slidably through said guide, and saidpair of load hoist cables being connected to said cage in spacedrelation at opposite sides of said tension hoist cable.

9. In motion compensating hoist mechanism as defined in claim 1, saidsupport structure having a boom projecting therefrom, said hoist meansbeing adjacent to said support structure, said boom having an outer endprovided with spaced cable guides for laterally spacing said cables,said pair of cables extending over a pair of said guides and said singlecable extending 'over one said guide located between said pair ofguides.

10. In motion compensating hoist mechanism including a support structureadapted to be mounted at a location over a vessel floating in the waterfor raising or lowering a load from or to said vessel, hoist means onsaid support structure including a load hoist and a tension hoist, drivemeans for releasably coupling said hoists for unitized operation, asource of power, slip clutch means for connecting said hoist means tosaid source of power for driving said hoist means, said tension hoisthaving cable means connectable to said vessel and slidably engaging saidload, and said load hoist having cable means connectable to said load,said tension hoist comprising a drum shaft, tension hoist drum meansrotatable with said shaft, said slip clutch means connecting said shaftto said source of power, said load hoist comprising a drum shaft, loadhoist drum means rotatable with said latter drum shaft, said drive meanscomprising clutch means for connecting said shafts for unitizedrotation, and means for selectively separately rotating said load hoistshaft, the improvement wherein the cable means of one of said hoistsincludes a pair of cables, the cable means of the other of said hoistcomprises a single cable disposed between said pair of cables.

11, In motion compensating hoist mechanism including a support structureadapted to be mounted at a location over a vessel floating in the waterfor raising or lowering a load from or to said vessel, hoist means onsaid support structure including a load hoist and a tension hoist, drivemeans for releasably coupling said hoists for unitized operation, asource of power, slip clutch means for connecting said hoist means tosaid source of power for driving said hoist means, said tension hoisthaving cable means connectable to said vessel and slidably engaging saidload, and said load hoist having cable means connectable to said load,clutch means for selectively driving said tension hoist and said loadhoist in unison, and separate drive means for driving said load hoist,the improvement wherein the cable means of one of said hoists includes apair of cables, the cable means of the other of said hoist comprises asingle cable disposed between said pair of cables.

1. In motion compensating hoist mechanism including a support structureadapted to be mounted at a location over a vessel floating in the waterfor raising or lowering a load from or to said vessel, hoist means onsaid support structure including a load hoist and a tension hoist, drivemeans for releasably coupling said hoists for unitized operation, asource of power, slip clutch means for connecting said hoist means tosaid source of power for driving said hoist means, said tension hoisthaving cable means connectable to said vessel and slidably engaging saidload, and said load hoist having cable means connectable to said load,fluid pressure operated means for varying the torque transmittingcapacity of said slip clutch means, pressure controller means forvarying the actuating fluid pressure to said fluid pressure operatedmeans, and load responsive means for operating said controller means tovary the pressure of actuating fluid to increase the torque transmittingcapacity of said slip clutch means when the tension on said tensionhoist cable means decreases and to decrease the torque transmittingcapacity of said slip clutch means when the tension on said tensionhoist cable means increases, the improvement wherein the cable means ofone of said hoists includes a pair of cables, the cable means of theother of said hoist comprises a single cable disposed between said pairof cables.
 2. In motion compensating hoist mechanism as defined in claim1, said cable means of said load hoist comprising said pair of cables.3. In motion compensating hoist mechanism as defined in claim 2, saidpair of cables being connectable to said load, and including equalizermeans associated with said pair of cables and said load for allowingsaid load to hang vertically between saId pair of cables when said loadhoist raises and lowers said pair of cables.
 4. In motion compensatinghoist mechanism as defined in claim 1, said cable means of said loadhoist comprising said pair of cables, a pair of drums disposed inaxially spaced relation, said pair of cables respectively being wound onsaid spaced drums.
 5. In motion compensating hoist mechanism as definedin claim 1, said load including a load support having guide meansthereon, said cable means of said tension hoist slidably extendingthrough said guide means.
 6. In motion compensating hoist mechanism asdefined in claim 5, said load support comprising an elevator cage.
 7. Inmotion compensating hoist mechanism as defined in claim 1, said cablemeans of said load hoist comprising said pair of cables, and said loadincluding a load support slidably engaging said cable of said tensionhoist.
 8. In motion compensating hoist mechanism as defined in claim 7,said load support comprising an elevator cage having a central cableguide, said tension hoist cable extending slidably through said guide,and said pair of load hoist cables being connected to said cage inspaced relation at opposite sides of said tension hoist cable.
 9. Inmotion compensating hoist mechanism as defined in claim 1, said supportstructure having a boom projecting therefrom, said hoist means beingadjacent to said support structure, said boom having an outer endprovided with spaced cable guides for laterally spacing said cables,said pair of cables extending over a pair of said guides and said singlecable extending over one said guide located between said pair of guides.10. In motion compensating hoist mechanism including a support structureadapted to be mounted at a location over a vessel floating in the waterfor raising or lowering a load from or to said vessel, hoist means onsaid support structure including a load hoist and a tension hoist, drivemeans for releasably coupling said hoists for unitized operation, asource of power, slip clutch means for connecting said hoist means tosaid source of power for driving said hoist means, said tension hoisthaving cable means connectable to said vessel and slidably engaging saidload, and said load hoist having cable means connectable to said load,said tension hoist comprising a drum shaft, tension hoist drum meansrotatable with said shaft, said slip clutch means connecting said shaftto said source of power, said load hoist comprising a drum shaft, loadhoist drum means rotatable with said latter drum shaft, said drive meanscomprising clutch means for connecting said shafts for unitizedrotation, and means for selectively separately rotating said load hoistshaft, the improvement wherein the cable means of one of said hoistsincludes a pair of cables, the cable means of the other of said hoistcomprises a single cable disposed between said pair of cables.
 11. Inmotion compensating hoist mechanism including a support structureadapted to be mounted at a location over a vessel floating in the waterfor raising or lowering a load from or to said vessel, hoist means onsaid support structure including a load hoist and a tension hoist, drivemeans for releasably coupling said hoists for unitized operation, asource of power, slip clutch means for connecting said hoist means tosaid source of power for driving said hoist means, said tension hoisthaving cable means connectable to said vessel and slidably engaging saidload, and said load hoist having cable means connectable to said load,clutch means for selectively driving said tension hoist and said loadhoist in unison, and separate drive means for driving said load hoist,the improvement wherein the cable means of one of said hoists includes apair of cables, the cable means of the other of said hoist comprises asingle cable disposed between said pair of cables.